Editing Command (computing) (section)

{{short description|External instruction to a computer program}}
{{redirect distinguish|System command|system call}}
{{other uses|Command (disambiguation)#Computing{{!}}Command § Computing}}
{{refimprove|date=May 2008 }}
In [[computing]], a '''command''' is an instruction received via an external [[Interface (computing)|interface]] that directs the behavior of a [[computer program]]. Commonly, commands are sent to a program via a [[command-line interface]], a [[scripting language|script]], a [[network protocol]], or as an event triggered in a [[graphical user interface]].

Many commands support arguments to specify input and to modify default behavior. Terminology and syntax varies but there are notable common approaches. Typically, an '''option''' or a '''flag''' is a name (without [[Whitespace character|whitespace]]) with a prefix such as [[dash]] or [[Slash (punctuation)|slash]] that modifies default behavior. An option might have a required value that follows it. Typically, flag refers to an option that does not have a following value. A '''parameter''' is an argument that specifies input to the command and its meaning is based on its position in the command line relative to other parameters; generally ignoring options. A parameter can specify anything, but often it specifies a [[file (computing)|file]] by [[filename|name]] or [[file path|path]].

The term ''command'' is sometimes also used for internal program instructions, but often other terms are more appropriate such as [[statement (programming)|statement]], [[Expression (computer science)|expression]], [[Function (computer programming)|function]], or [[Conditional (computer programming)|conditional]].<ref>Maurizio Gabbrielli, Simone Martini (2010). Programming Languages - Principles and Paradigms. Springer London, ''6.3.2 Conditional Commands'', p. 140</ref> For example, printing a message in Bash is via the ''command'' [[Printf (Unix)|printf]], while in Python it is via the ''function'' print().<ref>{{cite web | url =  https://docs.python.org/3/library/functions.html#print | access-date = 23 October 2023 | title = Built-in Functions - print | publisher = python.org }}</ref> Further, some aspects of adjacent technology are conflated with commands. For example, conditional logic in Bash and Python is called an ''expression''<ref>{{cite web | url =  https://docs.python.org/3/reference/expressions.html | access-date = 23 October 2023 | title = Conditional expressions | publisher = python.org }}</ref><ref>{{cite web | url =  https://www.gnu.org/software/bash/manual/html_node/Bash-Conditional-Expressions.html | access-date = 23 October 2023 | title = Bash Conditional expressions | publisher = gnu.org }}</ref> and ''statements'' in Java.<ref>{{cite web | url =  https://docs.oracle.com/javase/tutorial/java/nutsandbolts/if.html | access-date = 23 October 2023 | title = The if-then and if-then-else Statements | publisher = oracle.com }}</ref>